Should Gays have access to the same rights as heterosexuals?

Are there times or situations in which society should withhold or deny legal rights to certain persons? For instance, should a convicted felon be denied the right to vote? (15th Amendment Right). Or, should felons be allowed to have guns? (Second Amendment Right). I might venture to say that a person's behavior could create a legitimate basis for denying legal rights.

My challenge to the reader is this: Does Chief Justice Ronald M. George, writing the majority opinion, get it right when he wrote, “An individual’s sexual orientation — like a person’s race or gender — does not constitute a legitimate basis upon which to deny or withhold legal rights.”

I truly would like a thoughtful discussion to the following question: Is there a Constitutional Amendment that would be applicable, or, a reasonable interpretation, to support the denial or withholding of the legal right to marriage?